Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F10/00—Individual photovoltaic cells, e.g. solar cells
  • H10F10/10—Individual photovoltaic cells, e.g. solar cells having potential barriers
  • H10F10/16—Photovoltaic cells having only PN heterojunction potential barriers
  • H10F10/161—Photovoltaic cells having only PN heterojunction potential barriers comprising multiple PN heterojunctions, e.g. tandem cells
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F10/00—Individual photovoltaic cells, e.g. solar cells
  • H10F10/10—Individual photovoltaic cells, e.g. solar cells having potential barriers
  • H10F10/14—Photovoltaic cells having only PN homojunction potential barriers
  • H10F10/142—Photovoltaic cells having only PN homojunction potential barriers comprising multiple PN homojunctions, e.g. tandem cells
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F10/00—Individual photovoltaic cells, e.g. solar cells
  • H10F10/10—Individual photovoltaic cells, e.g. solar cells having potential barriers
  • H10F10/16—Photovoltaic cells having only PN heterojunction potential barriers
  • H10F10/164—Photovoltaic cells having only PN heterojunction potential barriers comprising heterojunctions with Group IV materials, e.g. ITO/Si or GaAs/SiGe photovoltaic cells
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F71/00—Manufacture or treatment of devices covered by this subclass
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F71/00—Manufacture or treatment of devices covered by this subclass
  • H10F71/127—The active layers comprising only Group III-V materials, e.g. GaAs or InP
  • H10F71/1272—The active layers comprising only Group III-V materials, e.g. GaAs or InP comprising at least three elements, e.g. GaAlAs or InGaAsP
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F71/00—Manufacture or treatment of devices covered by this subclass
  • H10F71/127—The active layers comprising only Group III-V materials, e.g. GaAs or InP
  • H10F71/1276—The active layers comprising only Group III-V materials, e.g. GaAs or InP comprising growth substrates not made of Group III-V materials
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F71/00—Manufacture or treatment of devices covered by this subclass
  • H10F71/139—Manufacture or treatment of devices covered by this subclass using temporary substrates
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F77/00—Constructional details of devices covered by this subclass
  • H10F77/30—Coatings
  • H10F77/306—Coatings for devices having potential barriers
  • H10F77/311—Coatings for devices having potential barriers for photovoltaic cells
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F77/00—Constructional details of devices covered by this subclass
  • H10F77/30—Coatings
  • H10F77/306—Coatings for devices having potential barriers
  • H10F77/311—Coatings for devices having potential barriers for photovoltaic cells
  • H10F77/315—Coatings for devices having potential barriers for photovoltaic cells the coatings being antireflective or having enhancing optical properties
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F77/00—Constructional details of devices covered by this subclass
  • H10F77/40—Optical elements or arrangements
  • H10F77/413—Optical elements or arrangements directly associated or integrated with the devices, e.g. back reflectors
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/50—Photovoltaic [PV] energy
  • Y02E10/544—Solar cells from Group III-V materials
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

• the present invention relates to a multi-junction solar cell having at least four pn junctions.
• the individual health cells have band gaps of 1.9 eV, 1.4 eV, 1.0 eV and 0.7 eV.
• the multiple solar cells according to the invention find application in space as well as in terrestrial
• the aim in the prior art is therefore to develop a quadruple solar cell with optimum bandgap energy for the AMI.5 or AMO solar spectrum.
• the optimum bandgap energies are in the range of: 1.9 eV / 1.4 eV / 1.0 eV / 0.7 eV.
• This type of quadruple solar cell is based on the conventional epitaxy of III-V multiple solar cells on germanium substrate.
• the only change to the current state of the art is the integration of an additional Teifzelle from the diluted nitrogen-containing Materia! Gallium indium nitride arsenide (GalnNAs).
• GaNAsSb gallium nitride arsenide antimonide
• BGalnAs boron gallium indium arsenide
• concentration of N or ⁇ is in the range of 2-4%.
• Ill-V compounds can be prepared which have a bandgap energy of 1.0 eV and can be grown lattice-matched to germanium.
• the big problem with this approach is the material quality of the diluted N- (or B) -based materials. So far, it has not been possible to produce solar cells with high efficiency and at the same time with the currently widespread method of organometallic vapor phase epitaxy. However, good results have been achieved with growth by molecular beam epitaxy. However, this method is characterized by significantly higher production costs for the solar cells and is therefore not used today in industrial production. A growth of
• GalnP / GalnAs / GalnNAs / Ge solar cells using metalorganic gas phase epitaxy is currently not in sight.
• Volz et al. and Friedman et al. Solar cells of this type are described (Volz, K. et al., Optimization of annealing conditions (Galn) (NAs) for solar cell applications, Journal of Crystal Growth, 2008, 310 (7-9): p.2222-8 and Volz et al., Development and Optimization of Al eV (Galn) (NAs) Solar Cell, in Proceedings of the 34th IEEE Photovoltaic Solar Energy Conference, 2009, Philadelphia, USA, and Friedman, DJ., et al.
• GalnAs Junction for a GalnP / GaAs / GalnAs (1 e V) / GalnAs (0.7 eV) Four-Junction Solar Cell, in Proceedings of the 4th World Conference on Photovoltaic Energy Conversion, 2006, Waikoloa, Hawaii, USA).
• GainP / GaAs / GalnAsP / GalnAs solar cell
• one half of the structure is grown on one gallium arsenide substrate and the other half on an indium phosphide substrate.
• Germanium and gaillium arsenide Germanium and gaillium arsenide.
• Bhusari et al. describes solar cells of this type (Bhusari, D., et al., Direct Semiconductor Bonding Technoiogy (SBT) for high efficiency Ilt-V multi-junction solar cells, in Proceedings of the 37th IEER Photovoltaic Specialisis Conference, 2011, Seattle, Washington, USA).
• SBT Direct Semiconductor Bonding Technoiogy
• the multiple solar cells according to the invention should have band gaps of 1.9 eV, 1.4 eV, 1.0 eV and 0.7 eV and at the same time show improved radiation stability.
• a multiple solar cell with at least four pn junctions containing a first, backside and a pn junction germanium subcell, a second and a third subcell of III-V semiconductors and at least one further, front Tei! Cell from III-V - Semiconductors provided.
• a multiple solar cell according to the invention is characterized in that the second subcell has a lattice constant which is at least 1% greater than the lattice constants of all other partial cells and the second subcell with the adjacent subcells via a metamorphic buffer layer for adapting the lattice constants of the adjacent subcells and on the opposite side of the second subcell is connected to the adjacent subcell via a wafer bonding connection.
• a further embodiment according to the invention relates to a multiple solar cell with at least four pn junctions comprising a first, backside and a pn junction germanium subcell, a second and a third subcell of ill-V semiconductors, and at least one further, frontal subcell from Illum.
• V semiconductors which is characterized in that the second subcell has a lattice constant which is greater by at least 1% than the lattice constant of all other subcells and the second subcell with the adjacent germanium subcell via a metamorphic buffer layer to adapt the lattice constant of the adjacent Partial cells and on the opposite side is connected via a Waferbond connection with the adjacent sub-cells.
• a multi-junction solar cell can be provided by combining epitaxial growth on two different substrates, metamorphic growth and wafer bonding.
• Three of the pn junctions in this structure are lattice-matched transitions to the germanium or gallium arsenide subcell because both crystals have a very similar lattice constant.
• These three pn junctions are the front subcell, the third subcell, and the back germanium subcell.
• Teiizellen now another subcell (the second subcell) is inserted with a bandgap energy of 1.0 eV.
• This second subcell has a significantly larger lattice constant compared to the materials of the other subcells.
• the lattice constant be gradually reduced from the lattice constant of the third subcell ⁇ e.g., by a metamorphic buffer.
• GaAs to the lattice constant of the second subcell (e.g., GalnAs) or from the lattice constant of the first subcell (e.g., Ge) to the lattice constant of the second subcell (e.g., GalnAs).
• the second subcell consists of gallium indium arsenide (GalnAs), gallium arsenide antimonide (GaAsSb), gallium indium arsenide phosphide (GalnAsP) or aluminum gallium indium arsenide (AIGalnAs).
• GaAsSb gallium arsenide antimonide
• GaAsP gallium indium arsenide phosphide
• AIGalnAs aluminum gallium indium arsenide
• the content of indium is preferably in the range from 10 to 80% by weight, particularly preferably in the range from 20 to 50% by weight .-%.
• the content of antimony is preferably in the range from 13 to 50% by weight.
• the second subcell has a bandgap energy between 0.7 eV and 1.4 eV, more preferably between 0.9 eV and 1.1 eV.
• the best results can be achieved with a second subcell with a bandgap energy of 1.0 eV.
• a further preferred embodiment provides that the second subcell has a lattice constant which is greater by at least 1%, preferably by 2 to 2.5%, than the lattice constants of all other subcells.
• the metamorphic buffer layer is preferably composed of gallium indium antimonide (GalnAs), alumintum galium indium arsenide (AIGalnAs), gallium indium phosphide (GalnP), aluminum gallium indium phosphide (AlGainP), gallium arsenide Antimonide (GaAsSb), aluminum arsenide anitmonide (AlAsSb), gallium phosphide antimonide (GaPSb) or aluminum phosphide antimonide (AlPSb) and may be either p- or n-type, depending on the location of the tunnel diodes, the Lattice constant through several steps or continuously from the lattice constant of the third partial line (eg GaAs) to the lattice constant.
• constant of the second subcell eg, GalnAs
• the lattice constant of the first subcell eg, Ge
• lattice constant of the second subcell
• the wafer-bonding connection between the affected sub-cells is electrically conductive and optically transparent.
• Optical transparency in the context of the present invention is to be understood as meaning a transmission of at least 80%, preferably of at least 95%, at wavelengths of at least 900 nm.
• the wafer-bonding connection can take place between two p-conducting or two n-conducting semiconductor layers, which preferably have a high doping.
• the third subcell is preferably gallium arsenide (GaAs), gallium indium arsenide (GalnAs), or aluminum gallium indium arsenide (AlGalnAs).
• the at least one further front-side subcell preferably consists of gallium indium phosphide (GalnP), aluminum gallium arsenide (AlGaAs) or aluminum-Gauminium indium phosphide (AlGalnP) or contains these substantially.
• a multiple solar cell is provided with four sub-cells, wherein the fourth Teiizelle represents a front partial line.
• one or more sub-cells are arranged between the front-side subcell and the third subcell, from which then multiple solar cells with five or more subcells can result.
• the individual subcells prefferably have further functional protective layers, in particular tunnel diodes for the electrical connection of the individual subsegments, barrier layers on the front and back of the subcells, highly doped contact layers, internal reflection layers and / or antireflection layers on the front side of the cell.
• the metamorphic buffer layer and the second subcell is grown on the first germanium Teiizelle.
• the third subcell of III-V semiconductors and the at least one further, front-side subcell are then grown separately therefrom and stabilized on the front side on a carrier (for example made of sapphire) by means of a detachable adhesive. These two subcell structures are then used between the second and third Operazelie means
• Wafer bonding connected. Subsequently, the carrier and the adhesive are removed.
• the metamorphic buffer layer and the second subcell is grown.
• the at least one further, front-side partial cell and the third partial cell made of III-V semiconductors are grown inversely on a GaAs or Ge substrate. These two subcell structures are subsequently connected by wafer bonding between the second and third subcell. Finally, the GaAs or Ge substrate is peeled off.
• the at least one more grown on the front part cell On a GaAs or Ge substrate, the at least one more grown on the front part cell. Subsequently, on the side facing away from the GaAs or Ge substrate side of the at least one front-side part cell, the third sub-cell of Il! -V semiconductors grown. On the third subcell, the metamorphic buffer layer and the second subcell are then grown on the side remote from the at least one further, front-side subcell.
• This subcell structure is connected to the surface of the second subcell with a first, separately produced germanium subcell by means of wafer bonding. Following the wafer bonding, the separation of the GaAs or Ge substrate takes place.
• GainP / GaAs / germanium can be integrated.
• the growth method of organometallic gas phase epitaxy can be used with their proven low cost.
• the structure benefits from the high radiation stability of the germanium subzelie for the wide-area application.
• the processing of multiple solar cells on germanium is still established in the industry, as well as the processing of the front. Herewith existing production processes can be used.
• the described approach is also cost-effective and interesting in terms of cost, if a GaAs substrate removal process ⁇ necessary for the growth of the upper sub-cells ⁇ can be found, which allows the substrate to be recycled several times for growth.
• the solar cells according to the invention can be used both for space applications and for use in terrestrial concentrator systems.
• the present invention has the advantage that established methods of metalorganic gas phase epitaxy can be used, which are based on epitaxial structures for GalnP, GaAs and germanium. Since the production of the contacts on the back side of the germanium partial cell and on the front side are also known and established, the conventional process chain can be kept so that the multiple solar cell according to the invention can easily be integrated into the existing production technology. Another significant advantage is that the Mehrfachsoielelie invention has a very high efficiency, since the bandgap energies of all sub-cells can be adjusted so that they are close to the theoretical optimum. For the space application, there is another advantage, since the germanium cell has a high radiation stability.
• Fig. 1 shows a first embodiment of the invention
• Fig. 2 shows a second embodiment of a Mehrfachsoielzelie invention.
• Fig. 3 shows a Mehrfachsoiarzelie invention with a
• Fig. 5 shows a wafer bond according to the invention between two semiconductors with different lattice constants.
• Fig. 1 is a multiple solar cell 1 with a rear side
• Germanium-Tetlzelle 2 shown. Onto this subcell a metamorphic buffer 3 and the second subcell of GalnAs have grown. The second subcell is connected to a third subcell 5 of gallium arsenide via a wafer bonding 10.
• the multiple solar cell has another front-side part cell 6 made of GalnP. Furthermore, tunnel diodes 11, 11 'and 11 "are integrated into the multi-junction solar cell for the electrical connection of the sub-cells.
• a second embodiment of the multi-junction solar cell 1 according to the invention is shown.
• This multiple solar cell is based on the inverted growth of the structure.
• the upper part of the multiple solar cell 1 ie the partial cell 6 made of GaInP and the partial cell 5 made of GaAs are first grown inverted on a substrate made of gallium arsenide.
• the metamorphic buffer 3 and the second subcell 4 of GalnAs are grown.
• the metamorphic buffer 3 was involved in the transfer of the lattice constant of GaAs to GalnAs.
• the rear germanium partial cell 2 is manufactured separately and then connected to the inverted grown solar cell structure of GalnP / GaAs / GalnAs via the wafer bond 10.
• tunnel diodes 11, 11 'and 11 "for the electrical connection of the metal cells are integrated into the multiple solar cell 1.
• the multiple solar cell 1 furthermore has a window layer 12, an antireflection layer 13 and front side contacts 14 and 14 'on.
• a multiple solar cell 1 according to the invention is shown in FIG.
• a sequence of layers on Ge with a lattice constant of 5.65 Angstrom is first prepared.
• the Ge sub-line 1 is generated by diffusion and growth of an AIGalnP window layer in the MOVPE reactor.
• a tunnel diode 11 "consisting of degenerate n- and p-type semiconductor layers is grown on the Ge subcell 2.
• the tunnel diode can be made of further
• GalnP buffer layer 3 in which the lattice constant of Ge up to Gao.71ino.29As is converted with a band gap energy of 1.0 eV.
• a transmission electron micrograph of such a buffer layer is shown in FIG. Due to the difference in the lattice constant of 2.3%, misfit dislocations occur which run horizontally through the buffer layer. These can be seen as dark lines in the TEM image. By a suitable choice of the growth conditions, the density of piercing dislocations can be kept so low that it is still possible to produce good quality solar cells on the buffer layers.
• the subcell consists of one
• Subcell 4 follows a highly doped n-Gao.71lno.29As bonding layer.
• a second layer sequence is deposited on a separate GaAs or Ge substrate.
• This first contains a release layer, which can later be used to separate the substrate from the solar cell structure.
• An example is an AlAs intermediate layer, which selectively reacts in hydrofluoric acid etch the remaining layers.
• This is followed by a GaAs contact layer with high doping, a partial cell 6 from Gao.5lno.5P, a tunnel diode 11, a GaAs or AlGaAs subcell 5 and a tunnel diode 11 '.
• the subcells and tunnel diodes can contain additional barrier layers with higher bandgap energy, as in the subcell 4 and the tunnel diode 11.
• All semiconductor layers of the layer sequence are lattice-matched to each other and have a lattice constant of about 5.65 angstroms.
• the two layer structures are now connected to one another via a wafer bond.
• a direct bond which fulfills the properties of transparency and very good conductivity.
• the two layer structures are deoxidized in a vacuum under bombardment with Ar atoms. This results in a 1-3 nm thin amorphous layer on the surface.
• the two layer structures are then pressed together at room temperature under a pressure of 5-10 kNewton. To increase the bonding energy further heating at temperatures of 100 - 500 ° C may be necessary. Furthermore, it is necessary to polish the surface of the layered structures if the surface roughness is worse than 1 nm.
• Such a direct wafer bond between two semiconductors with different lattice constants is shown in FIG. 5 in a transmission electron micrograph. One sees the amorphous intermediate layer at the bond interface.
• the GaAs or Ge substrate is removed from the layer structure and the solar cell is processed with contacts and antireflection layers.

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• 2012
  • 2012-03-08 DE DE102012004734A patent/DE102012004734A1/de not_active Withdrawn
• 2013
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